A novel differential protection scheme for distribution lines under weak synchronization conditions considering DG characteristics

A large number of DGs(distributed generators) in the ADN (active distribution network ) brings great uncertainty to power systems making it difficult quantify fault characteristics. Undoubtedly, setting traditional protection becomes more complex and difficult. Therefore, differential is an effective solution cope with it. However, requires high time synchronization, which be satisfied based on current communication conditions ADN. What’s more, accurate extraction fundamental frequency components also very considering distortion, offset, instability currents. In view this, a new scheme that makes full use information proposed this paper. First, pre-fault waveforms are taken as reference. Then similarity characteristics waveform sequences at both ends line calculated separately. Finally, weak synchronization constructed using Hausdorff distance, wide components. The only transmits calculation results instead sampling values, effectively avoids impact caused by data errors. Simulation shows can reliably identify internal faults various points protected external faults. Compared conventional protection, resistance transition up 30Ω, common ADNs. Moreover, has strong errors, withstand errors 20ms. excellent engineering application value, especially suitable for networks conditions.